| 12724538 |
McGinnis KM, Thomas SG, Soule JD, Strader LC, Zale JM, Sun TP, Steber CM: The Arabidopsis SLEEPY1 gene encodes a putative F-box subunit of an SCF E3 ubiquitin ligase. Plant Cell. 2003 May;15(5):1120-30.
The Arabidopsis SLY1 (SLEEPY1) gene positively regulates gibberellin (GA) signaling. Positional cloning of SLY1 revealed that it encodes a putative F-box protein. This result suggests that SLY1 is the F-box subunit of an SCF E3 ubiquitin ligase that regulates GA responses. The DELLA domain protein RGA (repressor of ga1-3) is a repressor of GA response that appears to undergo GA-stimulated protein degradation. RGA is a potential substrate of SLY1, because sly1 mutations cause a significant increase in RGA protein accumulation even after GA treatment. This result suggests SCF (SLY1)-targeted degradation of RGA through the 26S proteasome pathway. Further support for this model is provided by the observation that an rga null allele partially suppresses the sly1-10 mutant phenotype. The predicted SLY1 amino acid sequence is highly conserved among plants, indicating a key role in GA response. |
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